Balance-staff for watches.



No. 857,312. PATENTED JUNE18, 1907.

F. 0. SMITH. BALANCE STAFF FOR WATCHES.

APPLICATION FILED APB.26,19 06.

Z i Q WITNESSES: hffii'lifi' JNVENTOR.

- A TTORNE Y5 FREDERICK C. SMITH, OF NEW MILFORD, CONNECTICUT.

BALANCE-STAFF FOR WATCH ESn Specification of Letters Patent.

Patented June 18, 1907.

Application filed April 26,1906. Serial NO- 313,865

To all whom it pea/y concern:

Be it known that I, FREDERICK C. SMITH, a

citizen of the United States, residing at New Milford, in the county of Litchfield and State of Connecticut, have invented a new and useful Balance-Staff for WVatches, of which the following is a specification.

The present invention relates to improvements in watches, and more particularly to a balance staff for lever escapement watches.

With balance staff constructions with which I am acquainted, it is the practice d uring manufacturing or repair to rivet the balance wheel on the shoulder of the staff or a collar suitably secured thereto and striking a blow or more for accomplishing the riveting. This must necessarily throw the parts more or less out of true so that they have to be restored to their true condition of balance by a laborious and expensive process. According to another construction it is the practice to stake the roller table on the balance staff. It often happens that the roller table is too loose or too tight. When too loose it is liable to shift so that the watch is thrown out of beat and when too tight driving it on the staff sometimes results in splitting the roller table or bending the slender end of the staff. When with constructions of this character a pivot is broken it is necessary to drive out the staff and drive in a new one and then readjust. This matter consists in truing and poising the balance wheel and putting the hair spring and roller table in their relative positions. This process is delicate and d illicult for the average workman to accomplish besides being expensive and taking a great deal of time.

I overcome the objections above referred to by constructing the various parts so that they can be applied to the balance staff without riveting or staking them, and when the parts are once properly constructed there is no necessity of truing them since they true themselves when being secured together on the staff. To accomplish these results I provi de a staff having an annular flange which is shouldered, beveled or shaped frusto-conical and. construct the balancewheel with a socket in the arm thereof corresponding in shape to the annular flange. The wheel is held in place by means of the roller-table whose central opening is tapped so that the roller-table can be screwed on a thread cut on the staff. The roller-table screws down and clamps upon an intermediate collar or spacer that engages the balance wheel and holds it on the shoulder of the staff. By this arrangement any broken part of the balance wheel or balance staff can be repaired, or either of the members replaced without using any blows or other force tending to disturb the adjustment; to illustrate, for example, suppose a screw is broken off in the rim of a balance wheel, the whole wheel can be taken out to have the broken screw removedwithout endangering the delicate ends or pivots of the staff, and when the repair is finished the wheel can be readily replaced.

For a more complete understanding of the details of construction and combination of parts, reference is to be had to the following description, taken in connection with the accompanying drawings and to the claims appended hereto.

In the accompanying drawing which illustrates one embodiment of the invention,-

Figure 1 is a longitudinal section of the balance staff construction showing the staff in elevation. Fig. 2 is a perspective view of the staff, and Fig. 3 is a perspective view of the spacer.

Referring to the drawings, 1 represents the balance staff having pivots 2 at its ends. Intermediate the middle and upper end of the stafl is an annular flange 3 which is an inverted frustum of a cone forming a seat for the balance wheel. If desired, however, it can be of any other desired shape. 4 represents the arm of the balance-wheel which, at its center and in its upper surface, is provided with a socket 5 shaped to correspond to the contour of the flange 3 so as to accurately fit the same. Below the balance wheel is a collar or spacer 6 having transverse ends, the upper one 7 of which engages the under surface of the balance-wheel while the lower end 8 rests on the top of the roller-table 9. The upper end of the spacer 6 is provided with an axially-extending annular flange or boss 10 around which fits the unsocketed portion of the opening in the arm of the balance-wheel. This boss assists in centering the balance-wheel with respect to the staff. The opening 11 in the roller-table is tapped and the staff is provided with a thread 12 with which the thread of the opening en gages. It will thus be seen that the rollertable cooperates with the flange 3 to secure the balance-wheel in place, no riveting or staking being required. Above the flange 3 is a stud portion 13 which receives the collar of the balance spring. This collar is adapt ed to be held in place by frictional engagement with the stud portion 13. \Vith this construction, when it is desired to renew a staff, balance-wheel or repair either, all that is necessary is to unscrew the rollertable, after which the spacer and balance-wheel can be readily slid off the staff. After the repairs are effected the parts are assembled and secured together again with equal facility.

The staffs can be made for the market identical in measurement with old style solid staffs, so that when a watch has to be repaired by the renewal of a staff, my im-- proved staff can be readily employed. All the change that will be necessary for this purpose is the cutting of a socket in the upper surface of the balance wheel arm to receive the flange 5 of the staff. The threaded portion of the staff is of sufficiently larger diameter than the hole in the roller table of the watch mechanism being repaired that the hole can be tapped to fit the thread of the staff and leave shoulders above and below the balance arm and roller identical with the old style, so that the original hair spring stud fits perfectly, and the lower end of the staff below the roller gages exactly the same as in the old style.

I have described the principle of opera.

Having thus described the invention, what is claimed is 1. In combination, a balance-staff having an enlarged portion, a balance-wheel provided with a central socket on its top surface corresponding in shape to the said portion and bearing against the same, a screw thread on the staff a suitable distance below the wheel, a spacer freelyslidable over the thread and fitting on the portion of the staff between the thread and wheel and bearing at its top end on the under side of the latter and.

provided with an annular flange fitting into.

the opening of the wheel, and a roller table screwed upon the threaded portion of the staff and bearing against the lower end of the spacer for removably holding the latter and balance wheel in position.

2. In combination, a balance-staff having a frusto-conical portion, a balance -whccl provided with a central socket in its top surface corresponding to said portion and engaging the same, a screw-thread on the staff a suitable distance below the wheel, a s pacer slidable over the thread and fitting on the portion of the staff above the thread and engaging at one of its ends the side of the wheel opposite the socket, and a roller-table which screws on the threaded portion of the staff and engages the opposite end of the spacer to removably hold the latter and balance wheel in position.

In testimony that I claim the foregoing as my own, I have hereto affixed my signature in the presence of two witnesses:

FREDERICK C. SMITH.

itn esses:

M. C. ILBUR, EDWIN J. EMMONS. 

